Shoes, in particular, sports shoes, generally have a sole and a shoe upper. The sole of the shoe protects the foot from injuries, which may, for example, result from stepping on sharp objects. The sole may also increase the traction for the wearer of the shoe. The shoe upper holds the foot within the shoe and on the sole. Further, the shoe upper may provide stability to the foot, for example, by preventing the foot from twisting during fast movements. Moreover, the shoe upper may protect the foot from outside influences, such as water and dirt.
Shoe uppers and shoe soles have different requirements. Therefore, a sole is usually manufactured from a different material than a shoe upper, and the sole is attached to the shoe upper after manufacturing. Soles may, for example, be stitched, glued or nailed to shoe uppers. Also, a sole or a shoe upper often have different requirements that have to be met in different regions, thus the sole or the shoe upper may each be composed of several individual constituents.
Manufacturing methods for such multi-part shoes require that the individual constituents of the shoes are, for example, punched or cut in a multitude of separate fabrication steps. This not only leads to a labor-intensive and complex manufacturing method, but also produces a large amount of waste in the form of arising scraps. Moreover, the individual constituents have to be connected to each other, for example, stitched or glued, and often must be connected manually. This adds to the intensity and complexity of the labor. Furthermore, when gluing, for example, often solvents are used, which are harmful to the environment.
EP 2 815 668 A1 discloses a method for manufacturing a shoe, in which a sock-shaped base member is attached to a last portion. A molten resin is supplied and allowed to cure on the base member.
Various approaches are known for using injection molding for manufacturing a shoe.
DE 34 40 567 A1 discloses a sports shoe with an injected sole and injected pins.
U.S. Pat. No. 4,447,967 discloses a shoe, which is manufactured by injecting a plastic material onto a sock. In order to ensure a secure bonding of the plastic material and the sock, the sock comprises a base part formed of a less dense fabric, which is penetrated by mutually intersecting ribs of the plastic material.
However, the known approaches for injecting parts of shoes have several disadvantages regarding the stability of the shoe and, apart from that, technical implementations of the known approaches are difficult. In view of this background, it is an object of the present invention to improve the provision of shoes and soles by injection molding.